[gisborne]

If you are asking for the most general-purpose technology around right now, I would say Dart/Flutter.

Dart is a half-decent language, able to be used without excessive pain for mobile, desktop, web and backend development. It compiles to Javascript and WASM, as well as native code. And web can be either traditional HTML or a recreation of your mobile/desktop UI.

It’s a really healthy community with strong leadership and wide participation.

You’ll need SQL, but otherwise, you can build any kind of app with Dart and Flutter with reasonably fluidity.